In a conventional solar cell module including crystalline Si solar cells, a p-type region is provided on one of a front surface or a back surface of each of the solar cells, while an n-type region is provided on the other one of the front is surface or the back surface of each of the solar cells. In such solar cell modules, a front surface electrode provided on the front surface of one solar cell is connected to a back surface electrode provided on the back surface of a different solar cell adjacent to the one solar cell with wirings (e.g., Japanese Patent Publication No. 3670834 (see claim 1, [0017], FIG. 2, and the like).
In this solar cell module, the front surface electrode of the one solar cell is connected to the back surface electrode of the different solar cell with wirings. Thus, a processing for connecting the front surface and the back surface of the respective adjacent solar cells may cause a decrease in a positional accuracy of the wirings, a damage to the solar cells, or the like.
In contrast, as a technique for avoiding a processing for connecting front surfaces and back surfaces of each of the solar cells adjacent to each other, there has been a proposed technique in which solar cells are arranged by alternately inverting the polarities of the solar cells (e.g., Japanese Patent No. 3679611 (claim 1, [0007], and FIG. 2, and the like therein)).
More specifically, assume that a p-type region is provided on the front surface of one solar cell. In this case, an n-type region is provided on the front surface of a different solar cell adjacent to the one solar cell, and the front surface electrode provided on the front surface of the one solar cell is connected to the front surface electrode provided on the front surface of the different solar cell with the wirings. Thus, the processing for connecting the front surfaces and the back surfaces of each of the solar cells adjacent to each other can be avoided.
In addition, there has also been a proposed solar cell module in which both of a p-type region and an n-type region are provided on the back surface of a solar cell so that the solar cell does not need to locate the electrodes on the front surface thereof. This makes it possible to expand an area for receiving sunlight, and to improve a conversion efficiency.
In general, as an example of the soar cell module in which both of the p-type region and the n-type region are provided on the back surface of each of the solar cell, a solar cell module having a structure shown in FIG. 13 can be provided. FIG. 13 is a diagram showing the back surface of a solar cell module according to a conventional art.
As illustrated in FIG. 13, each of the solar cell has an n electrode 630, a p electrode 640, a metal piece 673 electrically connected to the n electrode 630, and an insulating region 675. In addition, the p electrode 640 of a solar cell a is connected to the n electrode 630 of a solar cell b with a plurality of tabs 671 (tab 671a to tab 671c) (e.g., A. Schoenecker, “A industrial multi-crystalline ewt solar cell with screen printed metallization,” the 14th European Photovoltaic Solar Energy Conference, Barcelona, 1997, page. 796-799).
However, in order to insulate the n electrode and the p electrode from each other, there are restrictions in shapes and arrangement of the n electrodes and the p electrodes in the above-described conventional art. Similarly, the shapes and the arrangements of the tabs used for connecting the solar cells to each other are also restricted.
Thus, in the conventional art, it has been difficult to improve the conversion efficiency by devising the shapes and the arrangements of each of the electrode, each of the tab, and the like.